docs: def plot(self, key=None, invert=None, plotmethod='imshow',
               cmap=plt.cm.gray, ms=4, Max=None,
               fs=None, dmargin=None, wintit=None,
               draw=True, connect=True):
          """ Plot the data content in a predefined figure  """
          dax, KH = _plot.Data_plot(self, key=key, invert=invert, Max=Max,
                                    plotmethod=plotmethod, cmap=cmap, ms=ms,
                                    fs=fs, dmargin=dmargin, wintit=wintit,
                                    draw=draw, connect=connect)
          return dax, KH